Degenerative stenosis is the second most common cardiovascular disease with an incidence of 2-7% in the Western European and North American populations aged beyond 65 years, as described in G. M. Feuchtner, W. Dichtl, et al. “Multislice Computed Tomography for Detection of Patients With Aortic Valve Stenosis and Quantification of Severity”, Journal of the American College of Cardiology 2006, 47 (7), 1410-1417. In the context of the present invention the term stenosis represents any abnormal narrowing of an artery. In interventional cardiology a degree of stenosis may be determined using fractional flow reserve (FFR) techniques in which a catheter is introduced into a coronary artery, which is able to measure a relative difference between pressure behind (distal to) and before (proximal to) a stenosis in the artery. Alternatively, medical imaging (such as computed tomography, NMR, PET and the like) may be used as a non-invasive method to determine a degree of stenosis by performing FFR calculations based on reconstructed arterial information. Interventional therapy to treat an arterial stenosis, such as ballooning or stenting, may be applied (directly) after the degree of stenosis is determined. Unfortunately it is not always possible to accurately and/or effectively plan the interventional therapy, since it is not always possible to determine the effect of the therapy beforehand. This may result in non-optimal results or may even require a follow-up interventional procedure, which, in both cases, is not in a patient's best interest.
To assist therapy planning a procedure known as virtual stenting is known in which stent placement is simulated based on determined or modeled artery dimensions and degree of stenosis. U.S. Pat. No. 8,157,742 discloses a procedure in which arterial dimensions and degree of stenosis are determined and modified using a previously obtained computed tomography scan and fractional flow reserves of a stenosed artery and its surroundings.
A drawback of such a procedure is that arterial dimensions and/or degree of stenosis are modeled with insufficient accuracy due to imaging errors (artifacts) and/or because certain assumptions made may be incorrect. Medical imaging of cardiac arteries is particularly complicated and prone to even more artifacts due to constant movement of the cardiac area. Further modeling is necessary to overcome this, for which further assumptions and corrections need to be made, causing further risks of not accurately determining the arterial dimensions and degree of stenosis before or after the virtual stent is placed, and, as a consequence, a physician may not select an optimal treatment.
The method of the present invention provides, amongst others, a solution to the previously stated problem.